Detailed Structure of Buried Glacial Landforms Revealed by High-resolution 3D Seismic Data in the SW Barents Sea

Abstract

Summary Glacial landforms identified in seismic 3D and multibeam data of the Barents Sea have improved the knowledge about past glaciations and associated geohazards. High-resolution P-Cable 3D seismic data were acquired in this area with an inline separation of 6 m, a source frequency range of 5–350 Hz and an source-receiver offset range of 120–160 m. Seabed images derived from the P-Cable data show an increased resolution and sharpness compared to images from conventional 3D seismic and multibeam echosounder data. High-resolution images of the buried Upper Regional Unconformity (URU) were derived from the P-Cable data, revealing previously unrecognized structures such as hill-hole pairs and rhombohedral and transverse ridges. These observations indicate different subglacial thermal regimes, the presence of permafrost, and a strong link with variations in the underlying geology. No reflections are imaged within the intraglacial sediment package in the conventional seismic data. However, reflections interpreted as the top of a shear margin moraine, shear planes, mass transport deposits, and soft beds are visible in the P-Cable data. Meter-scale glacial landforms and layers identified in the P-Cable cubes comprise new information about glacier dynamics, fluid flow, and faults, which are valuable for geotechnical and geohazard evaluations of offshore infrastructure.